To reduce the cost of making and distributing bread, distributors and bakeries recently adopted a method of freeze-storing baked bread at low temperature by introducing cooling air and then cooking the frozen bread to thaw and sell the bread restored to near fresh baked state. Referring to FIG. 11, conventionally, baked bread is stored frozen after the bread is baked in a baking process 11, and the baked bread whose surface temperature is 85° C. and above is cooled in a cooling process 21 for preliminarily cooling baked bread at high temperature in a cooling chamber at approximately −5° C. and below to make the surface temperature approximately 1 to 3° C. In a freeze-storing process 22, the cooled bread is frozen to about −20° C. and at 50 to 70% RH to prepare for storing.
Another related art discloses a method of freeze-storing bread while the bread is carried on a conveyor through a cooling chamber from an entrance to an exit and through a freezing chamber from an entrance to an exit. The conveyor carries bread thereon at a constant speed through the cooling chamber and the freezing chamber in which bread is cooled and frozen. According to this method, the bread is cooled in the cooling chamber while humidified air (pre-mixed with spray water) is supplied to the exit side and freeze-stored in the freezing chamber in which temperature is maintained at approximately −20° C. to be ready for the shipment.
Japanese patent publication JP 11-346644A proposes another method of freeze-storing baked bread and confectionery. Here, fresh cakes are quickly frozen to bring its core temperature to 0° C. and below, stored at −18° C. and below and at high humidity, and thawed in a cool room of 0° C.±2° C. and at 50 to 70% RH. Cakes include sponge cakes and bread made from dough containing more than 40% soluble sugar in weight ratio of solid ingredients. This publication, however, does not disclose a method of freeze-storing baked bread for a long period, retaining excellent quality of the crust (surface layer of bread), good sensory condition, and preventing crust flaking.
According to the inventors' tests, if the freezing process is performed for longer than a predetermined period, the baked bread processed by a conventional freeze-storing method shows crust staling and flaking, resulting in a weight decrease, thereby losing good texture and its commercial value. Moreover, In the conventional method, the exit side of the cooling chamber supplies humidified air, which is humidified by spraying cold water to air at room temperature. When water contained in the humidified air evaporates, taking evaporative latent heat from the surrounding, the ambient temperature decreases at the exit side of the cooling chamber, causing a temperature difference between the entrance side and exit side of the cooling chamber, which causes a drop in relative humidity inside the cooling chamber. This can deteriorate the quality of the baked bread.
There still remains a need for improving the quality of freeze-stored baked goods so that they can be restored more closely to their original baked condition, namely to retain excellent crust quality of baked food and also to prevent crust flaking while maintaining the quality and sensory condition of fresh baked food even after a long period of freeze-storing. The present invention addresses this need.